CHICAGO (AP) - Investigators trying to stop the first outbreak of monkeypox in the Western Hemisphere scoured seven states Tuesday for dozens of prairie dogs and other exotic pets sold by an Illinois distributor.

Health officials announced a total of five confirmed human cases of the disease - four in Wisconsin and one in Illinois. No people have died of the outbreak. In addition, 34 possible cases have been reported. Health and agriculture officials in Illinois, Indiana, Wisconsin, Pennsylvania, Texas, Ohio and South Carolina knocked on doors at homes and visited pet shops, trying to track animals sold to individuals and other pet stores by Phil's Pocket Pets in suburban Villa Park.

The investigators were tracking prairie dogs, rats, hedgehogs and other exotic pets, but the focus was on prairie dogs, the rodent that authorities believe is transmitting the disease to people.

"That's priority No. 1, identifying those people who purchased prairie dogs from this dealer," said Jeff Squibb, spokesman for the Illinois Department of Agriculture.

The investigators were seeking people who had bought exotic pets distributed since April by Pocket Pets, where a shipment of prairie dogs is believed to have been infected by a Gambian giant rat imported from Africa, where the disease is normally found.

The hunt was complicated by transfers of animals from dealer to dealer. Some of the animals were resold at swap meets, where few records are kept.

Squibb said 200 prairie dogs had been sent to Pocket Pets by a Texas dealer. Seventy had been put to death by Phillip Moberley, owner of Phil's Pocket Pets, he said.

Jim Rogers, spokesman for the U.S. Department of Agriculture, said investigators were using licensing and sales records to find out how the virus entered the United States.

A new possible human case of monkeypox was reported in New Jersey in an 11-year-old who had been in contact with a pet prairie dog while visiting in the Midwest, bringing the total possible cases to 34 - 16 in Wisconsin, 13 in Indiana and four in Illinois.

In Illinois, eight investigators were searching for 20 prairie dogs mostly in the Chicago area, Squibb said. The search appeared to be nearly complete, he said. Seven sick animals found in Illinois had been seized and put to death, Squibb said.

Eight other investigators were combing Indiana for as many as 32 customers who received animals distributed by Pocket Pets, said Margaret Joseph, spokeswoman for the Indiana State Department of Health.

Officials in Wisconsin said they believe they had found all but one of the 30 or so prairie dogs believed to have been sold to dealers in that state. Health officials in Pennsylvania were trying to track down two.

Monkeypox, which produces fever, rash, chills and aches, is a milder relative of smallpox. It has a mortality rate of one to 10 per cent in Africa, but no humans have died in the United States, and U.S. officials believe better nutrition and medical treatment probably will prevent deaths.

There have been no instances of the disease spreading from human to human in this outbreak. However, some people infected each other in a 1997 outbreak in Africa that afflicted hundreds.

The popularity of prairie dogs as pets has grown in recent years. Last year 10,000 were shipped out of Texas to become pets, said David Crawford, executive director of the Rocky Mountain Animal Defense.